This invention relates to apparatus for drilling holes in workpieces by means of radiant energy such as coherent light energy from a laser. While not limited thereto, the invention is particularly useful in the electronics manufacturing industry for drilling holes in integrated circuit substrates, printed circuit cards and the like.
The novel laser drilling apparatus described herein provides various advantages over previously known forms of laser drilling apparatus. It enables holes of highly accurate size to be drilled at a plurality of different locations on a workpiece without having to resort to the use of a hole pattern mask. It provides increased protection and safety for plant personnel who operate the apparatus or work in the vicinity thereof. It provides a cleaner and more efficient method for removal of the drilling debris. It protects critical optical elements from contamination by vapors and debris produced by the interaction of the laser beam with the workpiece material. And it enables quick and easy removal of a highly accurate hole size determining element for purposes of cleaning or replacing same.
A highly accurate hole size is obtained by providing a nozzle structure for passing a laser beam to the workpiece by way of a hole size defining aperture at the end of the nozzle structure and by placing such aperture up against the workpiece. Holes are drilled at different locations by changing the workpiece location at which the nozzle engages the workpiece. No hole pattern mask is required and a variety of different hole patterns can be accommodated in a flexible and efficient manner.
Increased operator safety is obtained by providing a nozzle structure which is placed up against the workpiece. As a consequence, the interaction of the laser beam with the workpiece material is not visible to the eye of the operator. The operator is shielded from both intense radiant energy and particles of drilling debris.
A continuously evacuated chamber located within the lower end of the nozzle provides a highly efficient method for the removal of drilling debris. The drilling debris is immediately sucked up into the evacuated chamber and removed by way of the vacuum pumping system. Among other things, this prevents drilling debris from being scattered over the workpiece and interfering with the drilling of other holes in the workpiece. It also provides for the immediate removal of any noxious or contamination-causing vapors produced by the interaction of the laser beam with the workpiece material.
The evacuated chamber in the lower end of the nozzle is separated from the workpiece by a removable metal disk having the hole size defining aperture in the center thereof. The laser beam passes through the aperture and onto the workpiece. The aperture defines the size of the hole drilled in the workpiece and, hence, may be of very small diameter for the case of very small holes. Thus, the diameter of the aperture may be, for example, as small as 0.001 inches. Thus, the aperture may require fairly frequent cleaning or replacement. This is greatly facilitated by having the aperture located in a removable disk. During drilling operations, the disk is held in place by the vacuum in the evacuated chamber. Thus, releasing the vacuum releases the disk and enables quick and easy removal of same for purposes of cleaning the aperture or replacing the disk with a new disk having a clean aperture.
For a better understanding of the present invention, together with other and further advantages and features thereof, reference is made to the following description taken in connection with the accompanying drawings, the scope of the invention being pointed out in the appended claims.